Field of the Invention
The present invention relates to a golf club shaft.
Description of the Related Art
A so-called carbon shaft has been known as a golf club shaft. A sheetwinding method has been known as a method for manufacturing the carbon shaft.
A prepreg includes a matrix resin and a fiber. Many types of prepregs exist. A variety of prepregs having different resin contents have been known. A variety of prepregs having different fibers have been known. In the present application, the prepreg is also referred to as a prepreg sheet or a sheet.
In the sheetwinding method, the type, shape, and disposal of a sheet, and the orientation of a fiber can be selected. The type of the prepreg can also be selected. A sheet constitution is designed corresponding to desired characteristics of a shaft.
A shaft including a plurality of hoop layers has been known. Japanese Patent application Laid-Open No. 11-19257 discloses a constitution in which three or four hoop layers are present in at least a part of a shaft. Japanese Patent Application Laid-Open No. 2009-22622 (US2009/0029792) discloses a shaft including a full length hoop layer and a partial reinforcing hoop layer.